1. Field of Invention
This invention relates generally to jet engines and more particularly to thrust chamber, reaction motor exhaust duct, and tailpipe cooling through a combination of heat dissipation via conduction transmission through a cryogenic non-propellant medium, injection of a cryogenic non-propellant medium, and ambient ram-air injection.
2. Description of the Prior Art
The plug-type exhaust system is widely known and it's main design feature is to block direct radiation of engine infrared, these systems solely rely upon air rammed by the fan or a ducted fan engine, collected by scoops to cool hot metal parts to reduce exhaust heat transmission to these parts. Plug-type exhaust systems also create turbine back-pressure penalties which result in power loss and heat build-up. Turbine cooling results in higher thrust output and efficiency in addition to cooling of the critical turbine blades. This has been accomplished by injecting a cryogenic fuel into the combustion chamber. This system can cause a fire hazard and more significantly does not suppress infrared emmissions. Heat exchangers have been employed using propellants as coolants situated in both the combustion chambers, thrust chambers, and exhaust ducts of reaction motors. Along with propellants, water has been suggested to circulate within channels or tubes machined into the walls of the aforementioned chambers and ducts. Cooling via the above regenerative cooling methods is well known. All of which are designed to cool-down the reaction motor walls and pre-heat the propellant(s). Also of interest is the design modification of the internal coolant channels in regenerative rocket combustors to improve combustor heat tolerance, enhance heat-transfer rates, and to extend the life-cycle of the components. All of the above cited references either do not address a solution for infrared thermal suppression, have limited-efficiency or cause turbine penalties. Most focus on combustion chambers. Furthermore, all of the systems cited use hazardous propellants as cooling mediums as opposed to inflammable cryogenic mediums. High exhaust temperatures of reaction motors must be countered with a volume of coolant at an absolute low temperature. Most importantly prior art depicts the exhaust duct as having smooth tapered walls which severely limit heat-transfer rates due to their limited surface area which is the medium for heat to coolant transfer. Other prior art known to the inventor does not disclose a device which will dissipate and significantly cool reaction motor exhaust, reduce exhaust decibels, and have no negative effect upon thrust and performance with regards to increasing turbine back-pressure.
Research in signature reduction techniques on aircraft have encompassed acoustic, optical, electronic, radar, and Infra-Red. Improvements have been made in all areas with the exception of Infra-Red (IR) suppression devices which are limited in efficiency. Infra-Red weapons systems are prolific worldwide both air-to-air and surface to air. As a measure of their impact, approximately 90 percent of all combat losses over the past 15 years are attributable to infra-red missiles.
The present system is designed for ATB (Advanced Tactical Bomber) and ATF (Advanced Tactical Fighter) stealth aircraft. Although applicable technology can be applied and refitted to any Military Aircraft, Surface Ships (Possibly Submersible Vessles) and Armored Vehicles.
The utility of the device is particularly great in Military Aircraft where detection by hostile forces is a prime and unwanted factor. The main concept is to elude look-up and look-down Infra-Red sensors as well as forward looking Infrared (FLIR) devices.